Sinking of deep boreholes by rotary flushing - comprises lowering drill string contg. rotary drill end bit, into the hole then passing flushing fluid through the string

摘要

This is a method for sinking a deep borehole by the rotary flush method. A drill string, consisting of a number of drill pipes hanging from a hook, is lowered into the hole. The bottom pipe carried a rotary drill-bit driven either by the drill string or directly. The drill string, through which a flushing fluid passes down to the bit, is weighted at its bottom end. The string is divided into hydrostatically independent sections, each end of which is subjected to the hydraulic pressure of the flushing fluid in the borehole. The stirng is in tension, except around the weighted tool. A number of features of the method, and variants of the arrangement used, are claimed. USE/ADVANTAGE - In other methods of sinking deep borings, borehole deviations can be reduced but not eliminated, and the methods may be expensive. With this method, straight boreholes can be sunk without undue expense; the equipment is lighter and hook load is reduced.